This application claims the priority of German Patent Document 197 05 5280.0.
The invention relates to a fiber-reinforced molded plastic part as well as to a process for its manufacture, both being known from the article on which this application is based and which has the title "Materials in Automobile Construction", published in the German Special Edition of Automobiletechnische Zeitunq (ATZ), July/August 1996, Page 74-77.
From the article, a fiber-reinforced molded plastic part is known which is formed of a plastic matrix and of natural fibers which are embedded in the plastic matrix. In order to ensure a good disposal of the molded plastic parts, the plastic matrix consists of so-called biopolymers which are natural organic macromolecules and are obtained from reproducible raw materials, such as sugar beets, potatoes, corn, cellulose or used paper. Natural fibers are those fibers which are obtained from nature as reproducible raw materials. Molded plastic parts of this type of construction, when being disposed of, are biologically degradable without any reservations because all their organic constituents will decay, and in the decaying cycle, will be converted into water, CO.sub.2, humus and biomass. Bacteria and fungi will grow in the decay. CO.sub.2 formed during the decaying process is neutral, in the ecological balance, because it had previously been taken from the atmosphere for producing the raw materials.
However, when these molded parts are used, they are susceptible to biological stress which is why they are not completely suitable for use as high-quality and durable molded parts. Normally, these molded plastic parts are especially protected for use as durable high-quality molded parts. These are particularly useful in the automobile industry. This takes place by applying a protective coating, such as lacquers, or such polymers are selected as biopolymers, which have a slow decay process. But, a coating which protects from biological stress has substances which cause ecological concern; during disposal, the slow decaying process requires a lot of time and disposal space or a high-expenditure comporting facility.
It is an object of the invention to further develop a molded plastic part such that, while it can be disposed of in a simple manner and without ecological reservations, it can also be used as a durable high-quality molded plastic part. Furthermore, it is an object to develop a process by which such molded plastic parts can be manufactured.
With respect to the molded plastic part on which this invention is based, this object is achieved by a fiber-reinforced molded plastic part, the part having at least 80% raw materials by weight, the part comprising a plastic matrix having natural fibers, the plastic matrix comprising at least one biopolymer and at least one polymer, the at least one polymer being largely resistant to biological stress. A process is also provided. By using biopolymers which are, for the most part, enclosed by polymers which are largely resistant to biological stress, components manufactured from such materials have a good stability. Furthermore, after their useful life, they can either be recycled with respect to their material, for example, by a new thermoplastic processing, optionally separated according to the biopolymer and the resistant polymer, or can be jointly subjected to a CO.sub.2 -neutral degrading process.